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WO2003090400A1 - Systeme et procede de determination d'information de rythme a partir d'un signal a ondes porteuse multiples - Google Patents

Systeme et procede de determination d'information de rythme a partir d'un signal a ondes porteuse multiples Download PDF

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Publication number
WO2003090400A1
WO2003090400A1 PCT/GB2002/001747 GB0201747W WO03090400A1 WO 2003090400 A1 WO2003090400 A1 WO 2003090400A1 GB 0201747 W GB0201747 W GB 0201747W WO 03090400 A1 WO03090400 A1 WO 03090400A1
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WIPO (PCT)
Prior art keywords
signal
timing information
correlation function
location
symbols
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Ceased
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PCT/GB2002/001747
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English (en)
Inventor
Douglas Roger Pulley
Matthew Collins
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Conexant Systems LLC
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Conexant Systems LLC
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Publication date
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Priority to PCT/GB2002/001747 priority Critical patent/WO2003090400A1/fr
Priority to AU2002251290A priority patent/AU2002251290A1/en
Publication of WO2003090400A1 publication Critical patent/WO2003090400A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2662—Symbol synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2676—Blind, i.e. without using known symbols
    • H04L27/2678—Blind, i.e. without using known symbols using cyclostationarities, e.g. cyclic prefix or postfix
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
    • H04L27/2607—Cyclic extensions

Definitions

  • This invention relates generally to multi-carrier signals, and, more specifically, to determining timing information from a multi-carrier signal.
  • a multi-carrier signal is one in which an incoming stream of bits or symbols is divided up into groupings, each with a lower data rate, with each grouping used to modulate a different carrier. The modulated signals are then combined together to form a transmission signal.
  • a multi-carrier signal is an attractive mechanism to deal with the problem of multi-path, in which multiple delayed echos of the original transmitted signal give rise to intersymbol interference. That is because the increased delay between successive symbols made possible by dividing the incoming data stream into groupings can be made large in relation to the duration of the time period over which the echos are received, thus reducing or eliminating the problem of intersymbol interference.
  • Orthogonal frequency division multiplexing is a form of multi-carrier signaling in which the groupings of a data stream modulate densely packed subcarriers with overlapping spectra, and in which modulation of the multiple subcarriers occurs algorithmically through fast Fourier transform (FFT) techniques.
  • FFT fast Fourier transform
  • a serial-to-parallel converter divides an incoming stream of symbols into a plurality of parallel streams.
  • An inverse fast Fourier transform (FFT) circuit then performs an inverse FFT on the parallel streams.
  • a parallel-to-serial converter combines the inversely transformed streams in a serial stream.
  • a modulator then modulates a carrier signal with the serial stream. The modulated carrier is then transmitted over the communications interface.
  • OFDM frequency division multiple access
  • DAB digital audio broadcasting
  • DVD-T digital video broadcasting - terrestrial
  • OFDM even though the spectra of the subcarriers overlap, orthogonality between the different groupings is maintained through the nature of the modulation which is performed, which is QAM, and also through appropriate spacing of the subcarriers. Together, these factors ensure that the spectra of adjacent subcarriers, which are in the form of a sine function, are such that the peaks of a spectrum for one subcarrier lie on the zeroes of spectra for the other subcarriers.
  • cyclic prefix guard bands are added in the time domain to the active zones representing each symbol to ensure that intersymbol interference is reduced to tolerable levels even with a limited number of subcarriers. Additional information on OFDM is available in "Data Transmission by Frequency- Division Multiplexing Using the Discrete Fourier Transform," S. B. Weinstein and P. M. Ebert, IEEE Transactions on Communication Technology, Nol. COM-19, No. 5, October 1971, pp. 628-634, which is hereby fully incorporated by reference herein as through set forth in full.
  • the transmitter and receiver in a multi-carrier signaling communications system must be synchronized, both in time and in frequency. To synchronize itself, the receiver must acquire timing information from the multi-carrier signal. Unfortunately, due to intersymbol interference caused by multi-path, the acquisition of timing information from the multi-carrier signal is often difficult.
  • the invention provides a system for and method of determining timing information from a signal representing a plurality of symbols.
  • One or more of the symbols may be represented in the signal by a first portion and a second portion, wherein the first portion is derived from the second portion.
  • a correlation function is determined from the signal which may be repeating over a symbol period.
  • One or more symbol periods of the correlation function may be analyzed, and one or more predetermined features of the correlation function detected within these symbol periods.
  • the timing information may then be derived from the locations of these one or more predetermined features.
  • the locations of the one or more of the detected features relative to expected locations are determined.
  • the one or more of the relative locations are weighted, and one or more of the weighted relative locations are averaged to produce information from which the timing information is derived.
  • the signal representing the plurality of symbols is derived from a multi-carrier signal received over a communiations interface.
  • the multi- carrier signal may be an orthogonal frequency division multiplexed (OFDM) signal.
  • the received signal is demodulated into a baseband signal utilizing a local oscillator signal.
  • the result is a time domain signal representing a plurality of symbols from which the timing information is derived. This timing information is used to update the frequency of the local oscillator signal in the receiver.
  • a detector may update the timing information once, intermittently, or periodically although, in a typical application, the timing information is updated periodically. In one example, the timing information is updated every symbol.
  • each of the symbols is represented in the time domain by a guard band appended to an active zone, where the guard band comprises G samples derived from the active zone. These G samples may be taken from the end of the active zone to form a cyclic prefix which is appended to the beginning of the active zone.
  • a correlator continuously runs, sample by sample, to determine the correlation between samples i to i+G-1 with the samples i+A to i+A+G-1, where i is a variable, A is the number of samples in the active zone, and G is the number of samples in the guard band.
  • the resulting correlation values C(i) form a correlation function which repeats every A+G samples.
  • x is a complex sample of the signal (digital) representing a plurality of symbols
  • x is its logical complement
  • A is the number of samples in the active zone
  • G is the number of samples in the guard band.
  • a number N of periods of the correlation function may be analyzed, where N is an integer greater than 1.
  • One or more peaks of the correlation function in these N periods may be detected, and the locations of the one or more detected peaks relative to expected locations may be determined.
  • One or more of the relative peak locations may be weighted using a weighting function which, in order to eliminate or reduce the effect of outliers, progressively weights relative locations less the more they deviate from the expected locations.
  • One or more of the weighted relative locations may then be averaged to produce an offset value which may be used to update the expected peak location for future symbol periods.
  • the timing information may then be derived from this expected peak location.
  • the expected peak location of the correlation function within a symbol period is updated every N symbols, but the value of the correlation function at this expected peak location is used to update the frequency of the local oscillator signal every symbol. More specifically, the phase of the correlation function at the expected peak location is used to update the frequency of the local oscillator signal by adding to this frequency the following value: ⁇ • Fsubcarrier I2 » ⁇ where ⁇ is the measured phase of the correlation function (in radians) at the expected peak location, and Fsubcarrier is the distance (in radians per second) between the subcarriers in the signal.
  • phase ⁇ of the value of the correlation function at the expected peak location, C(i ) may be computed in accordance with the following expression:
  • FIG. 1 is a simplified block diagram of a multi-carrier signal receiver.
  • FIG. 2A is a block diagram of a first embodiment of a detector according to the invention.
  • FIG. 2B is a block diagram of a second embodiment of a detector according to the invention.
  • FIG. 3 is a diagram of one example format of the signal which is input to the detector of FIG. 2.
  • FIG. 4 is an idealized rendering of the correlation function which results from a signal having the format depicted in FIG. 3.
  • FIGs. 5A-5C illustrate real world distortions which can occur in relation to the correlation function of FIG. 4.
  • FIG. 6 is an example of a weighting function configured to eliminate outliers.
  • FIG. 7A is a flowchart of a first embodiment of a method according to the invention.
  • FIG. 7B is a flowchart of a second embodiment of a method according to the invention.
  • the application which will be described is a system for updating the frequency of a local oscillator signal used for demodulating a multi-carrier signal received over a communications channel, which may be a wireline or wireless communications channel.
  • a block diagram of the system 100 is illustrated in Figure 1.
  • the multi- carrier signal is received over a communications channel and provided on signal line 102 to demodulator 104.
  • the other input to demodulator 104 is a local oscillator signal provided by local oscillator 108. This signal is provided as an input to the demodulator 104 over signal line 106.
  • the demodulator 104 demodulates the received signal using the local oscillator signal to produce an output signal having a high frequency component and a baseband component.
  • the high frequency component is filtered out using a low pass filter (not shown). The result is a baseband signal provided on signal line 118.
  • the baseband signal is input to transformation circuitry 110.
  • transformation circuitry 110 is fast Fourier transform (FFT) circuitry configured to take the FFT of baseband signal 118, thereby inverting the effects of the inverse FFT typically applied at the transmitter.
  • FFT fast Fourier transform
  • the output of transformation circuitry is provided on signal line 112.
  • the baseband signal on signal line 118 is a time domain signal representing a plurality of symbols.
  • This signal is provided as an input to detector 114.
  • Detector 114 is configured determine timing information which is provided as an input to Automatic Frequency Control (AFC) loop 116.
  • AFC loop 116 adjusts the frequency of the local oscillator signal provided on signal line 106 responsive to the timing information provided by detector 114.
  • AFC Automatic Frequency Control
  • a feedback loop is provided for updating the frequency of the local oscillator signal responsive to the timing information provided by detector 114.
  • a first embodiment of the invention comprises a detector for detecting timing information from a time domain signal representing a plurality of symbols.
  • One or more of the symbols may each be represented by a first portion and a second portion, with the first portion derived from the second portion.
  • This embodiment is illustrated in block diagram form in Figure 2A.
  • the signal representing a plurality of symbols is provided as an input over signal line 202 to correlator 204.
  • Correlator 204 correlates various portions of the signal together to determine a correlation function.
  • the correlator 204 may correlate the first and second portions together to produce a repeating correlation function, i.e., one that has one or more features which repeat every symbol or other period, even though, due to real world factors such as noise and multi-path, but also because of variations in the signal itself, the function may not exactly repeat from period to period.
  • a repeating correlation function i.e., one that has one or more features which repeat every symbol or other period, even though, due to real world factors such as noise and multi-path, but also because of variations in the signal itself, the function may not exactly repeat from period to period.
  • Feature detector 206 then analyzes one or more periods of the correlation function, and detects over these one or more periods, one or more predetermined features of the correlation function.
  • This predetermined feature may be the peak of the correlation function or some other feature such as a trough, inflection point, flat section, or the like.
  • Logic 224 which may be hardware, software, or a combination of hardware and software, then derives the timing information from the locations of the one or more detected features of the correlation function. This timing information is then output on signal line 222.
  • Figure 2B is a block diagram of a second embodiment of a detector according to the invention.
  • Blocks 204 and 206 are identical to the like-numbered blocks in the first embodiment of Figure 2A, and so a discussion of these blocks need not be repeated.
  • logic 224 in this embodiment is of a more specific structure than in the first embodiment. Accordingly, the discussion here will focus on this element.
  • the locations of the one or more detected features is determined by feature detector 206, and input to comparator 210.
  • the other input to comparator 210 is the expected locations of the one or more detected features as provided by block 208.
  • block 208 may determine the expected locations of the one or more features based on the locations of these features in the past in conjunction with the size of the period of the correlation function. For example, if the correlation function repeats every period, and the feature of the correlation function which repeats is its peak, the peak location in future periods can be expected to occur at a previous location plus one or more periods of the correlation function.
  • Comparator 210 compares the locations of the one or more features with their expected locations, and, in response, outputs relative locations of one or more of the features, i.e., locations of the features relative to their expected locations.
  • Weighter 212 weights one or more of the relative locations using weights which may or may not be dependent on the values of the relative locations, and which may or may not be distinct from unity.
  • Averager 214 then averages one or more of the weighted relative locations to produce an average offset, which is a measure of the degree to which the actual feature location deviates on average from its expected location.
  • This average offset is provided as an input to block 208, which uses this information to update the expected feature location for future periods.
  • Block 220 may then derived phase information from the updated expected feature location. This phase information constitutes timing information which is output on signal line 222.
  • Each of the elements of the detector embodiments of Figures 2A-2B may be implemented in hardware, software, or a combination of hardware and software.
  • the elements are implemented in the form of one or more ASICS chips.
  • the elements are implemented in the form of instructions executable by a DSP or other processor.
  • the signal which is input to the detector is depicted in Figure 3.
  • the signal represents a plurality of symbols, each represented by a portion of the signal comprising a guard band of G complex samples and an active zone of A complex samples.
  • the guard band for a symbol may be G complex samples taken from the end of the active portion of the symbol and appended to the beginning of the active portion, this forming a cyclic prefix to the active portion.
  • the number of samples per symbol in a DVB-T OFDM signal may be 2112 samples. Of this total, 2048 samples may be assigned to the active portion A, and 64 samples may be allocated to the guard band G.
  • the correlator in this embodiment continuously runs, sample by sample, to determine the correlation C(i) between samples i to i+G-1 with the samples i+A to i+A+G-1, where i is a variable, A is the number of samples in the active zone, and G is the number of samples in the guard band.
  • this process may be represented as follows: (G-
  • C ⁇ i) ⁇ *(z + ; x(J + 7 + A) * (1) -°
  • x is a complex sample of the signal (digital) representing a plurality of symbols
  • x * is its logical complement
  • • refers to the multiplication operation
  • A is the number of samples in the active zone
  • G is the number of samples in the guard band.
  • the correlation function is periodic, consisting of triangular sections of length 2G, where G is the size of a guard band.
  • the triangular sections are spaced from one another by length A-G, where A is the size of the active zone.
  • the correlation function reaches a peak in the middle of each of the triangular portions. This corresponds to the situation in which the index i in equation (1) is pointing at the beginning (leftmost sample) of a symbol in the signal of Figure 3. This will result in the correlation being taken between two identical portions of the signal. As the index i deviates from this location, the correlation between the corresponding portions of the signal will be less because the corresponding portions of the signal will overlap less.
  • a peak detector then examines N periods of the correlation function, where N is an integer greater than 1. From these N periods, the peak detector detects one or more peaks of the correlation function, and a comparator outputs the location of one or more of the detected peaks relative to an expected peak location.
  • the expected location can be determined by examining the peaks locations of one or more previous periods of the correlation function, and then using that information, in conjunction with the number of samples in a symbol, to estimate the peak location for future sample periods.
  • the process of peak detection may be complicated due to the presence of intersymbol interference caused by multipath. Because of this factor, and also because of intended variations in the time domain signal from symbol to symbol, the triangular portions of the correlation function may be distorted.
  • Figure 5A shows a triangular portion of the correlation function over which is superimposed an echo of itself (shown in phantom in Figure 5A).
  • This echo represents the effects of multipath.
  • the resulting signal may thus appear as shown in Figures 5B or 5C.
  • Figure 5B a peak has been replaced by a flat portion
  • Figure 5C the peak has been replaced by two peaks. Either way, the process of peak detection is complicated.
  • the relative locations may be weighted using a weighting function which is designed to eliminate outliers.
  • a weighting function which is designed to eliminate outliers.
  • Figure 6 As illustrated, relative locations representing large deviations from expected locations are weighted less, while relative locations representing small deviations from expected locations are weighted more. The result is to remove large outliers from consideration.
  • One or more of the weighted relative locations may then be averaged together to determine the timing information. This averaging may also help account for the effects of multipath particularly with the pattern of Figure 5C.
  • the first peak 500 may be detected as the peak for the symbol, while, for other symbol periods, the second peak 502 may be detected as the peak for the symbol.
  • the peak location may ultimately be detected to occur somewhere in the middle of the two, i.e., the position identified with numeral 504.
  • N periods of the correlation function which may each be equal in size to a symbol, are examined at a time.
  • the correlation function corresponding to these symbols is examined, and an attempt made to locate a peak of the correlation function in each of these N periods.
  • the relative locations of each of these peaks are then determined, and to account for outliers, these relative locations are then weighted using a weighting scheme geared to eliminate outliers.
  • the weighted relative locations are then averaged together over the N symbols to determine an average offset to the expected peak location. This information may then be used to updated the expected peak location for future symbol periods. This process then repeats for the next N symbols.
  • the net result in this implementation is that the expected peak location is updated every N symbols.
  • the value of the correlation function, C(i ), at this expected peak location is examined every period. Since the correlation function is a complex function, the value C(i ) will have real and imaginary portions, Re[C(i )] and
  • phase ⁇ of C(i ) may then be computed in accordance with the following expression:
  • this phase is proportional to the LO frequency offset, and is used by the AFC loop to update the frequency of the LO signal every symbol.
  • the LO frequency is updated by adding to it the following value: ⁇ • Fsubcarrier I2* ⁇ (3) where ⁇ is the measured phase of the correlation function (in radians) at the expected peak location, and Fsubcarrier is the distance (in radians per second) between the subcarriers in the signal.
  • a first-in-first-out (FIFO) buffer having length N is maintained in the detector.
  • This buffer is updated with the weighted relative location of the peak for each new symbol that is received.
  • the buffer holds the weighted relative locations of the peaks for the N most recent symbols. Every time the buffer is updated, the contents are averaged to produce an average expected offset which may be used to update the expected peak location every symbol.
  • the phase information for updating the frequency of the local oscillator signal may then be updated as in the previous embodiment.
  • FIG. 7A A flowchart of one embodiment of a method according to the invention is illustrated in Figure 7A. As illustrated, the method begins with step 702 in which a correlation function is determined from a signal representing a plurality of symbols.
  • one or more of the symbols may each be represented by a first portion and a second portion, with the first portion being derived from the second portion.
  • the correlation function may be determined by correlating portions of the signal together or with a predetermined sequence. In one implementation, the correlation function is determined by correlating for each symbol the first and second portions together, and repeats every symbol.
  • one or more symbols are each represented by cyclic prefix guard band G appended to an active zone A, and the correlation C(i) is continuously determined, sample by sample, between samples i to i+G-1 with the samples i+A to i+A+G-1, in accordance with expression (1) above.
  • Step 702 is followed by step 704.
  • step 704 an effort is made to detect one or more predetermined features of the correlation function such as a peak or a flat portion.
  • N successive periods of the correlation function are analyzed, where N is an integer greater than 1, and an effort made to locate the peaks of the correlation function for each of these symbol periods.
  • Step 704 is followed by step 706.
  • step 706 timing information is derived from the locations of the one or more of the detected features from step 704.
  • FIG. 7B is a flowchart of a second embodiment of a method according to the invention.
  • the first two steps are steps 702 and 704, which are identical to the like- numbered steps discussed in relation to the previous embodiment. Accordingly, they need not be discussed further here.
  • Step 704 is followed by step 708, in which the locations of the one or more features detected in step 704 are determined relative to expected locations.
  • Step 708 is followed by step 710, in which one or more of the relative locations determined in step 708 are weighted in such a way as to remove outliers. Again, this step may employ a weighting function of the type depicted in Figure 6.
  • Step 710 is followed by step 712, in which one or more of the weighted relative locations are averaged to produce average offset information.
  • step 712 is followed by step 714, in which the timing information is derived from the average offset information.
  • the average offset information from step 712 is used to update the expected peak location every N symbols, where N is an integer greater than 1.
  • the timing information in this example is the phase ⁇ of the correlation function at the expected peak location, C(i ). This timing information may be determined every sample even though the expected peak location is only updated every N symbols.
  • the method of Figure 7B is successively performed over N non-overlapping periods of the correlation function.
  • the result in this implementation is that the expected peak location will be updated every N symbols.
  • the method of Figure 7B is successively performed over N at least partly overlapping symbol periods.
  • the result is that the expected peak location in this implementation will be updated more frequently than every N symbols.
  • the method is performed every symbol period using the correlation function from the N most recent symbol periods.
  • the expected peak location is updated every symbol.

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  • Computer Networks & Wireless Communication (AREA)
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Abstract

La présente invention a trait à un système et un procédé de détermination d'information de rythme à partir d'un signal représentatif d'une pluralité de symboles. Un ou plusieurs des symbole représentés peut chacun être représenté par une première portion et une deuxième portion, la première portion étant dérivée de la deuxième portion. Une fonction de corrélation est déterminée à partir du signal (204). La fonction de corrélation peut être une corrélation répétée déterminée par la corrélation des portions correspondant aux première et deuxième portions d'un ou de plusieurs symboles. Une ou plusieurs éléments prédéterminés sont détectés à partir de la fonction de corrélation (206). L'information de rythme est dérivée à partir des emplacements d'une ou de plusieurs éléments détectés (224). Dans une application, le signal représentatif de la pluralité de symboles est dérivé d'un signal à ondes multiporteuses reçu sur une interface de communications. Le signal à ondes multiporteuses peut être un signal de multiplexage fréquentiel optique (OFDM). Le signal reçu est démodulé en un signal de bande de base au moyen d'un signal d'oscillateur local. Le signal représentatif d'une pluralité de symboles est le signal de bande de base. L'information de rythme obtenue à partir du signal peut être utilisée pour la mise à jour de la fréquence du signal d'oscillateur local.
PCT/GB2002/001747 2002-04-19 2002-04-19 Systeme et procede de determination d'information de rythme a partir d'un signal a ondes porteuse multiples Ceased WO2003090400A1 (fr)

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AU2002251290A AU2002251290A1 (en) 2002-04-19 2002-04-19 System for and method of determining timing information from a multi-carrier signal

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004059941A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen eines Eintreffzeitpunktes einer Empfangsfolge
DE102004059946A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Ermitteln eines Korrelationsmaximums
US7525483B2 (en) 2004-12-13 2009-04-28 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Receive device and method for receiving a receive sequence
FR2993123A1 (fr) * 2012-07-03 2014-01-10 Distribeo Procede, dispositif et programme d'ordinateur pour la detection d'horloge dans un signal acoustique module par deplacement de frequence
US10944535B2 (en) 2019-05-29 2021-03-09 Shure Acquisition Holdings, Inc. OFDMA baseband clock synchronization

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0996237A1 (fr) * 1998-10-19 2000-04-26 Lucent Technologies Inc. Estimation de temps de rafales GSM à la base de valeurs moyennes déterminées au préalable
US20020009166A1 (en) * 2000-06-02 2002-01-24 Johannes Steffens Process for synchronization
US6363128B1 (en) * 1996-09-02 2002-03-26 Stmicroelectronics N.V. Multi-carrier transmission systems

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6363128B1 (en) * 1996-09-02 2002-03-26 Stmicroelectronics N.V. Multi-carrier transmission systems
EP0996237A1 (fr) * 1998-10-19 2000-04-26 Lucent Technologies Inc. Estimation de temps de rafales GSM à la base de valeurs moyennes déterminées au préalable
US20020009166A1 (en) * 2000-06-02 2002-01-24 Johannes Steffens Process for synchronization

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004059941A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen eines Eintreffzeitpunktes einer Empfangsfolge
DE102004059946A1 (de) * 2004-12-13 2006-06-14 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Ermitteln eines Korrelationsmaximums
DE102004059946B4 (de) * 2004-12-13 2008-10-02 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Ermitteln eines Korrelationsmaximums
US7525483B2 (en) 2004-12-13 2009-04-28 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Receive device and method for receiving a receive sequence
US7627063B2 (en) 2004-12-13 2009-12-01 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Device and method for determining a time of arrival of a receive sequence
US7649936B2 (en) 2004-12-13 2010-01-19 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Device and method for determining a correlation maximum
AU2005315886B2 (en) * 2004-12-13 2010-04-22 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V. Device and method for determining an arrival moment of a reception sequence
FR2993123A1 (fr) * 2012-07-03 2014-01-10 Distribeo Procede, dispositif et programme d'ordinateur pour la detection d'horloge dans un signal acoustique module par deplacement de frequence
US10944535B2 (en) 2019-05-29 2021-03-09 Shure Acquisition Holdings, Inc. OFDMA baseband clock synchronization
US11343066B2 (en) 2019-05-29 2022-05-24 Shure Acquisition Holdings, Inc. OFDMA baseband clock synchronization

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